The Arizona sentinel., 1887-12-10

green. A mixture of white and black
in proper proportions will give to the
blind the same sensation as the
different shades of red and green. 1t
is somewhat singular that while there
is no reason to doubt that color blind
ness is as old as man, it was not dis
tinctly recognized and accurately &c
scribed until little more than hun
dred years ago.
The first case on record is that OF
shoemaker named Harris, who lived in
Mavport, England. 1t is said that his
first suspicion of any peculiarly OF
vision on his part arose when he was
about four years old. Having by acct
dent found child's stocking IN the
street he carried it to Il house near by
TO inquire for the owner. he noticed
that other people called it red stock
ing, but could not understand why
thew did so. as it seemed to him COM
pletely described by calling it n
stocking, He observed, also, that
while the children with whom
he played could distinguish
the cherries on a tree by some pre-
tended difference of color, he could
only tell them from the leaves by their
difference in size and shape. He found,
too that by means of this difference in
color, OF in some way which he could
not understand, they could see the
cherries at Il greater distance than he
could, though i'll cases where their
sight was not assisted by the color.
he could see objects at as great dis
lance as any of them.
This case was described in 1777.
Seventeen years later the celebrated
English chemist, Dalton, described his
own case so accurately and minutely
that color blindness in general, and
especially the form of it with which he
was afflicted namely. red blindness
has since been known as DaltOniSm.
He says that he was never convinced
of any REGULARITY of his vision until he
accidentally observed the color of the
flower geraniunl zOnGle by candlelight.
The flower was pink, but appeared 10
him almost an exact sky-blue by day.
Bv the light of the candle, however, it
seemed to him not to have any blue in
it, being what he called red-a color
which forms striking contrast 10
blue. His friends. to whom he re-
ferred the matter, agreed that the
color was not materially different from
what it was by daylight. except his
brother, who was subject to the same
defect rs himself Two years after
ward he began to investigate the sub
| iect of colors. or color-blindness. He
found that he could distinguish but
two, or at most three, colors in the
rainbow. These were yellow and
blue. or yellow, blue and purple. His
yellow included the green, yellow.
orange and red of others. This was
the same Dr. Dalton who afterwards,
though Quaker and conscientiously
opposed 10 wearing bright colOrs, when
he had received the scarlet gown
of n doctor of laws for presenta-
ton at court, not only donned it with
out objection, but also wore it for sew
eral days upon the street. in happy
unconsciousness of the effect which he
produced.
Color-blindness is largely hereditary,
and affects males much more frequent
ly than females. 1t exists from birth,
and there is no means known by which
it can be remedied. A temporary
condition of color-blindness is occa-
sionally met with, due to disease or
injury. which passes away with the
condition which produced it. The
existence of color-blindness in persons
occupying responsible positions in the
railroad and marine services is q
source of great danger TO the travel
ing public. and in most countries ex,
aminations are provided by law, fol
the purpose of testing the color-per
ception of all applicants for these
positions. Golden Days.